The present invention is directed to a seat support mechanism for a tiltable chair utilizing interconnected torsion bars to vary the resistance to rearward tilt. Numerous arrangements of this general type are shown in the prior art U.S. Pat. Nos. 2,991,125, 3,131,904, 3,480,249, 3,592,433, 3,740,792, 3,868,144, 4,295,626, 4,479,679, 4,653,806, 4,718,726, 4,744,600, 4,773,706 and 4,892,354. None of these patents discloses the features of the present invention.